if you're a backpackers' style of traveler, it's ok to travel alone. SE Asia people is mostly nice and welcome to any tourists. Just be aware of your belongings especially your wallet and travel documents. For safety, leave your travel documents in your rooms' safe deposit box or your accommodation's receptionist. Don't bring too much money in your bag while you travel within the city. But if you aren't comfortable to travel alone and never had experiences before, I suggest you travel with a group. Just book your trip to your travel agent. Have a nice and safe trip !